This invention relates to an engine load parameter-calculating system, and an engine control system using the engine load parameter-calculating system.
Conventionally, a method has been proposed by Japanese Provisional Patent Publication (Kokai) No. 63-143348, which comprises steps of detecting an amount of air drawn into an internal combustion engine by an intake air amount sensor or an intake pressure sensor, and controlling a fuel supply amount, ignition timing, etc. in accordance with the detected value of the amount of air drawn into the engine. When the engine is in a transient operating condition, a proper control amount cannot be obtained due to delay in detection of the amount of air by the intake air amount sensor or the intake pressure sensor. Therefore, according to the above method, when the engine is in a transient operating condition, an estimated value of intake pressure is obtained from detected values of throttle valve opening and the engine rotational speed, and a control amount is obtained based on the estimated value of intake pressure.
However, according to this prior art, estimated values of intake pressure are stored in a storage device in the form of a map set in accordance with values of the throttle valve opening and the engine rotational speed. To obtain an accurate estimated value of intake pressure, the map is required to have many finely divided values (lattice points) of the throttle valve opening and the engine rotational speed. This requires the use of a storage device with a very large capacity. Further, it takes a longer time period to determine a control amount from such a very large amount of stored data, which results in degraded controllability of the engine.